Mixing 2" with 1 1/2" plumbing at valves

Miranda

Well-known member
Jan 20, 2008
161
Northeast Florida
I am replumbing my AGP and my setup includes three 3-way pentair valves. The valves are designed to take 1 1/2" pipe on the inside flange or 2" pipe on the outside flange. My plan is to connect to/between all valves using 2" elbows and tees (slip/thread type) and then transition down to 1 1/2 for the pipe runs to/from the equipment and pool (using 2" male thread/1 1/2" female slip fitting). My reason is for ease of repair (threaded fittings will save the valves if repair is needed) and I figure the reduced drag through the elbows is a good thing too. The fittings on the filter and pump are 1 1/2" so everything else (pump to filter, etc) will be 1 1/2" . The only 2" pieces will be the elbows and Tees that connect to valves.

Is there a down side to this plan? My fear is that the mixing of pipe sizes will cause it to sing, scream or moan. Any need for concern? My pump is a 1.5 hp Matrix Powerflo 2-speed, always run on high.
 

Melt In The Sun

TFP Expert
LifeTime Supporter
Oct 29, 2009
3,899
Tucson, AZ
Why not make the whole run 2" then downsize at the ends? The system will be more efficient that way. Otherwise, you rplan sounds OK to me.

Why do you run your pump on high all the time? Seems like a huge waste of electricity.
 

JasonLion

TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
37,880
Silver Spring, MD
You can mix pipe sizes like that if you want. As Melt In The Sun says, the entire system will be a little more efficient if you use 2" pipe throughout. What many people do is to use 2" pipe on the equipment pad and 1.5" pipe elsewhere.

I don't recommend using threaded fittings like that. Threaded fittings can leak if you don't get them together just right. Glued fittings are easier and more reliable. All you need to allow for future changes is a length of straight pipe where you could make a cut and glue on a new fitting.
 

Miranda

Well-known member
Jan 20, 2008
161
Northeast Florida
I run it on high because it is a huge 33' aboveground with a wimpy little skimmer and a single return beside it. On low speed the far side gets no movement at all. I just added another return about 1/3 of the way around, so hopefully that will help. I wanted to upgrade the skimmer, but there are no real choices for AGP's.

It is pretty efficient since the equipment is right beside the pool in a tight area under the edge of the deck. With valves, unions and liquidator tap ins, there's nothing long enough to cut and recouple, and I don't want to have to buy new valves if I have to fix/change anything. Those 3-was are expensive!

Would 2" all around be possibly TOO efficient? Is there such a thing? With the old plumbing I had to restrict my skimmer line with a valve just to get the liquidator to flow since there was no suction in the suction line since the skimmer run is so short and free.

I was thinking of using 2" for the long run to the new return, will that help balance the flow with the shorter return run of 1 1/2? There is a 3-way between them, but I don't want to have to choke the other one down just to get them matched..

As for the threads, I am concerned about leaks, but at least they will be fixable.....when I plumbed it last time I got leaks at the pump and returns, and had to cut everything out to redo it all since the other ends were all glued. This time I will go heavy on the HD teflon tape and hope for the best. Mainly I just want to uyse threaded where needed to save the valves.
 

Miranda

Well-known member
Jan 20, 2008
161
Northeast Florida
It is up and running. No noise, leaks, which is pretty amazing concerning all the threaded fittings! I went with 2" for the skimmer line and the new return on the other side of the pool, 1 1/2" for the original return and the auxilary port that are very close to the pump. (The auxilary port is about 8" below the original return. It is selectable with a valve (to choose suction or pressure) depending on need for vac/cleaner or extra return) Everything is running smoothly. Thanks for all the help!
 

Miranda

Well-known member
Jan 20, 2008
161
Northeast Florida
It isn't the prettiest setup, nor the most efficient (losts of elbows and tees close together) , but it accomplishes what I wanted it to in a small amount of space.

[attachment=0:1el32hm9]overall.jpg[/attachment:1el32hm9]

The two white valves are suction and return cutoff, making it easy to empty/clean the pump basket, and control flow if desired. I have two returns and one "auxilary port" 8" below the original return that is selectable as pressure or suction. The black pentair valves are all three-way. The leftmost top one selects/mixes between the return on the far side of the pool, and the original return + aux port. The rightmost top one selects/mixes between the original return and the aux port when used as a return or pressure cleaning port. The bottom valve selects between the skimmer, and the aux port when it is used as a vacuum port. I can choose several configurations, with 1, 2 or all three returns flowing, a pressure side cleaner attached to the aux port while the other returns flow, or a vacuum cleaner attached to the aux port while other returns flow. I also have a redneck fountain I can hook up in one of the ports. The tubing is for the liquidator.
 

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